Jill makes up a fiendish plan to surprise Gwen on her birthday but is surprised herself by an unexpected turn of events.

"Second-grader Brian and his sister Penny, a kindergartner who he calls Pea Brain, [try] to discover who is undermining School Spirit Week. Readers will have a good chance of solving this mystery, which features...the lively, but fundamentally good-natured, rivalry between Brian and Penny."—H.